The purpose of the study is to determine if learned control can be achieved over stomach hydrochloric acid secretions. Peptic ulcer subjects will attempt to monitor and control their own acid secretions through the biofeedback of their stomach pH changes. In a series of training sessions subjects will attempt to increase their pH with and without feedback of their stomach functions. During this period gastric contents will be continuously aspirated and measured for concentration and volume changes. The study will further attempt to measure any central and autonomic nervous system correlates to learned changes in stomach pH. Electroencephalograph, electromyograph, and stomach motility measures will be simultaneously recorded during training. The study is designed to investigate also, personality patterns among subjects who are successful or unsuccessful at learning to control their own acid secretions. In an effort to determine the effectiveness of biofeedback as a viable tool, the study will also control for the effects of the subject's instructional set and the placebo effect.